Nutritional composition and techno-functionality of non-defatted and defatted flour of edible insect Arsenura armida.

Edible insects are traditional foods worldwide, and in Mexico, is a prehispanic practice. Nowadays, edible insects can be a food source for the increasing population. This research aimed to evaluate the nutritional profile, physical and techno-functional characteristics of non-defatted (NDF) and defatted (DF) flour of the edible insect Arsenura armida to use as a functional ingredient. The lipid content in NDF was 24.18%. Both flours are high in protein, 20.36% in NDF and 46.89% in DF; their soluble proteins from A. armida were classified according to their molecular weight, which ranged from 12 to 94 kDa. The physical properties suggest that both flours have good flow characteristics. Regarding techno-functional properties, DF had the highest water (275.6%) and oil (121%) holding capacity values. The viscosity values indicate that they behave as a non-Newtonian shear-thinning fluid at a high concentration (20%). Emulsion capacity values range between 78.3 and 100% in both flours, with stability between 92.4 and 100%. These flours could be a good source of nutrients, and their techno-functional properties make them a good option for animal protein substitutes.

The insertion of bioactive peptides at the C-terminal end of an 11S globulin changes the structural stability and improves the antihypertensive activity

BACKGROUND: The 11S globulin from amaranth is the most abundant storage protein in mature seeds and is well recognized for its nutritional value. We used this globulin to engineer a new protein by adding a four valinetyrosine antihypertensive peptide at its C-terminal end to improve its functionality. The new protein was named AMR5 and expressed in the Escherichia coli BL21-CodonPlus(DE3)-RIL strain using a custom medium (F8PW) designed for this work. RESULTS: The alternative medium allowed for the production of 652 mg/L expressed protein at the flask level, mostly in an insoluble form, and this protein was subjected to in vitro refolding. The spectrometric analysis suggests that the protein adopts a ß/α structure with a small increment of α-helix conformation relative to the native amaranth 11S globulin. Thermal and urea denaturation experiments determined apparent Tm and C1/2 values of 50.4°C and 3.04 M, respectively, thus indicating that the antihypertensive peptide insertion destabilized the modified protein relative to the native one. AMR5 hydrolyzed by trypsin and chymotrypsin showed 14- and 1.3-fold stronger inhibitory activity against angiotensin I-converting enzyme (IC50 of 0.034 mg/mL) than the unmodified protein and the previously reported amaranth acidic subunit modified with antihypertensive peptides, respectively. CONCLUSION: The inserted peptide decreases the structural stability of amaranth 11S globulin and improves its antihypertensive activity.

Overexpression of a modified amaranth protein in Escherichia coli with minimal media and lactose as inducer.

In this research it was attempted to overexpress the acidic subunit, from the 11S amaranth seed globulin termed amarantin, modified with antihypertensive peptides in Escherichia coli Rosetta (DE3) by manipulating some factors in batch fermenter such as growth medium composition, inducer (isopropyl ß-D-thiogalactopyranoside [IPTG] or lactose), air flow, cultivation temperature, agitation speed and induction time. The possibility of using several minimal media and lactose as inducer to increase yields of the recombinant protein was investigated. Previous fermentations at flask level showed that two minimal culture media (A6 and A7) and 0.5% (w/v) lactose presented high yields of the engineered protein expression. Thus, the latter two media were tested at fermenter level, the lactose inducer, and different environmental conditions. Factors with significant effects were identified by Plackett-Burman design with center points and were adjusted at the level suggested and the yields of the recombinant protein were increased from 303.2 to 1,531 mg L(-1) in A6 and from 363.4 to 1,681 mg L(-1) in A7. Unlike some patents where the highest productivity was achieved at 24 h or afterwards, in this research the best productivity of the recombinant acidic subunit was attained at 4 and 6 h of induction using both media, respectively.